Borges Carlos1, Palma Carla1, Morgado Vanessa1, Walsham Pamela2, Kivimae

Caroline3, Parmentier Koen4, Crum Steven5, McGovern Evin6 and Dickson Andrew7

1Hydrographic Institute – Navy Rua das Trinas 49, 1249-093 Lisboa, Portugal; E-mail: carlos.borges@hidrografico.pt; 2Scottish

Government, Marine Scotland Science, 375 Victoria Road, Aberdeen AB11 9DB UK; 3National Oceanography Centre, European Way,

Southampton, SO14 3ZH, UK; 4Royal Belgian Institute of Natural Sciences, Directorate Natural Environment, Marine Environment, 3de

en 23ste Linieregimentsplein, 8400 Oostende, Belgium; 5Quasimeme, Wageningen UR,PO Box 8005,NL-6700 EC, Wageningen, The

Netherlands; 6Marine Institute, Rinville, Oranmore, Co. Galway.H91 R673, Ireland.; 7MPL,Scripps Institution of Oceanography, UC San

Diego,9500 Gilman Drive #0244,La Jolla CA, 92093-0244 USA

Background: Ocean acidification (OA) due to oceanic uptake of anthropogenic carbon dioxide (CO2) emissions to the

atmosphere is expected to have significant consequences for future marine ecosystems. OA is a long-term process resulting in

decreasing pH, carbonate ion concentration, and calcium carbonate saturation states and increasing pCO2. The requirement

to accurately observe these changes to the ocean carbonate system requires robust harmonised procedures for sampling and

analysis are followed and that good practice in quality assurance is in place. A workshop, sponsored by OSPAR and

QUASIMEME was held in the National Oceanographic Centre in the UK in February 2016 with the focus on developing best

practices for sampling, sample pre-treatment, sample storage of water samples collected for dissolved inorganic carbon (DIC),

total alkalinity (TA), pH and pCO2 analysis. The workshop also considered Quality assurance requirements.

Workshop conclusions and on-going developments:

• Guidance provided on sample handling and correct use of reference materials.

• Identified need for alternative biocide to mercuric chloride and recommended a guidance for the preparation of a local

reference material be produced.

• Identified need for Reference Material for range of water types: open ocean, estuarine, etc.

• Identified the urgent need for Proficiency Testing Scheme or regular intercalibration exercise. QUASIMEME are

developing a proficiency test material in 2017 with a view to running a proficiency testing scheme in 2018.

REFERENCE 1. Dickson, A.G., Sabine, C.L. and Christian, J.R. (Eds.) 2007. Guide to best practices for ocean CO2 measurements. PICES Special Publication 3, 191 pp. (http://cdiac.ornl.gov/oceans/Handbook_2007.html).

Quality Assurance - Reference Materials

• Currently only 1 reference material producer for

TA and DIC- Scripps Institution of Oceanography

(SIO) from a single location.

Correct Use of Reference Materials:

• There is currently no standard available for TA or

DIC analysis and laboratories are typically using

the SIO reference material as primary standard.

Sampling & Storage

Sampling - methods are well established and workshop

recommended following the Guide to best practices for Ocean

CO2 measurements1.

Recommended

Bottle type

Borosilicate glass i.e Pyrex with ground

glass stopper. 250 – 500 mL capacity.

Bottle Washing to

prevent growth of

bacteria resistant to

the preservative

After use, it is recommended that bottles be

washed in dishwasher and undergo high

temperature ashing or are rinsed with acid.

Sample

Preservation

Currently the only biocide recommend for

sample preservation, which will not alter the

alkalinity of the sample, is mercuric chloride.

Gas Exchange

Prevention

Grease bottle stoppers and secure in bottle

by means of clip or tape.

Sample Storage

If preservation with a biocide is not possible,

analyse samples immediately.

Preserved samples - store in the dark at

room temperature (< 20°C) for no longer

than 3 years.

Quality Assurance (QA) for Inorganic Carbon System

Measurements in the Context of Ocean Acidification

(OA) Monitoring and on-going International

developments

Proficiency testing/Intercalibration

• Currently no routine proficiency testing

scheme/regular intercalibration exercise.

• Previous SIO intercalibration exercise highlighted

issues when waters different to those of the SIO

reference material were analysed.

• Recommend intercalibration exercise covering

regional waters.

• Workshop suggested European PT provider such

as QUASIMEME may be able develop suitable

proficiency testing scheme.

• If the reference material

is used as a primary

standard a secondary

quality control procedure

should be introduced

i.e using local reference

material.